OK, a few questions. For first time visual use(ie. not photography) a dob as large as you can afford is almost always the way to go especially if you are interested in deep sky observing, as opposed to planets or the moon. The don't get me wrong, dobs do well on solar system observing, they just excel at deep sky.
The black diamond I assume is just the scope without a mount, as they don't sell dob mounts seperately, probably not the best option.
As a dob is simply a newtonion scope, it can useually be mounted on an EQ mount, but if it is collaspible, then it would not be as easy as usually rings are used around the body of the scope.
The collapsible Sky watcher scope are very, very VERY easy to set up,and save on space in the house and in the car if going to an observing night, star party etc. Solid tubes are cheaper and can give you more aperture for your $$$, as as we all know.... aperture always wins.
Once you get to 10 inches or bigger, the tube is BIG!!!
, so even if space is not a problem, you need to be confident about picking up and handling a large scope.
Hope this helps!
Malcolm
